Pain is an unpleasant sensory and emotional experience arising from actual or potential tissue damage. Pain is highly subjective to the individual experiencing it, but medical diagnosis is based on characterising it in various ways such as the duration, severity, type (dull, burning or stabbing), and location in body. Experiencing pain is influenced by a number of dynamic, changing and interacting physical, mental, biochemical, physiological, psychological, social, cultural and emotional factors. Thus, pain perceived as intense at one time may at another time be perceived as less intense although all other factors appear to be constant.
Pain management divides symptoms into acute or chronic pain. Acute pain is distinguished from chronic pain. Acute pain warns the patient that something is wrong, and may result from a variety of causes including tissue damage, infection and/or inflammation. Chronic pain, on the other hand, may have no apparent cause or may be caused by a developing illness or imbalance. Sometimes chronic pain can have a psychosomatic or psychogenic cause.
Surgical procedures often result in some form of acute pain. Surgical pain may include nociceptive, neuropathic or psychological components. Nociceptive pain is a pain experienced as a result of nociception, which is detection of a stimulus by a pain receptor (nociceptor) and transmission of the information to the brain along nerves. Nociceptive pain is caused by tissue damage and inflammation in response to trauma. The resulting pain is usually not well localized and is opioid responsive.
The goal of post-surgical pain management is twofold: i) to provide a quick onset of analgesic or pain relief and ii) to reduce or modulate the quality and intensity of pain a patient experiences in the post-surgical period. The improvement in minimally invasive surgical techniques has resulted in a reduction in patient time in a hospital and has shifted many procedures to the physician's office. Outpatient surgery has become a procedure of choice for many simple to complex procedures, such as bunionectomy, knee surgery, hernia repair, tonsillectomy, carpel tunnel release, cataract removal, hysterectomy and prostatectomy. The patient must now be made comfortable enough in a short period of time to return home and safely manage his or her own pain. Medications that provide gradual but extended response to acute pain situation are often inappropriate in this situation. Treatment for acute pain after bunionectomy surgery typically consists of opioid and/or NSAIDs/COX-2 inhibitors. In some cases, opioids are given for several days and then the subject is treated with an NSAID or COX-2 Inhibitor. However, interest in the cardiovascular risk associated with the use of COX-2 inhibitors has become intense, especially in regard to rofecoxib and celecoxib. While current treatments for management of post-surgical acute pain are useful, there is a need for improved methods for treating post-surgical acute pain, particularly following bunionectomy, which provides immediate relief of acute pain with little or no risk of a cardiovascular event.